Numerical Study of Flow Separation Control over a Hump Airfoil Using a Novel Sweeping Jet Actuator

Abstract

Sweeping jet (SWJ) actuators have become a hot research topic in flow control due to their larger sweep range and higher control efficiency. However, the linear relationship between frequency and velocity ratio (VR = Ujet/U∞) in the SWJ actuator makes it challenging to determine the dominant factor affecting the control effect. Decoupling the frequency and VR and determining the control mechanism of the SWJ actuator is, therefore, a difficult task. In this study, a novel type of SWJ actuator was designed using periodic synthetic jets instead of feedback channels. This achieved the implementation of different frequencies under the same VR, effectively decoupling frequency and VR. The SWJ actuator was then applied in flow separation control of a Hump airfoil, with F+ = f × c/U∞ = 0.375, F+ = 1, and F+ = 10 being the three forcing frequencies studied. Numerical results demonstrated that all three forcing frequencies displayed a control effect on flow separation. At VR = 1.8, the control effectiveness is optimal for F+ = 1, and as VR continues to increase, F+ = 10 becomes the optimal control frequency.

Keywords

• flow separation control
• sweeping jet
• synthetic jet
• frequency